This invention generally pertains to coupler systems for railroad cars and the like. More specifically, the present invention relates to a biased pin retainer block for a rotary coupler system. While the invention is particularly applicable to use the type F rotary couplers described herein, it will be appreciated by those skilled in the art that the invention has broader applications and may also be adapted for use in other coupler environments.
After the introduction of the rotary coupling system, a train comprised of loaded railroad cars of the open top or hopper type (which may contain coal, ore, etc.) could be emptied without having to uncouple and separate the cars. This was accomplished by rotating each car up to 180.degree. about its longitudinal centerline while it remained connected on both ends to the next adjacent cars to thereby more efficiently accommodate gravity emptying. Such coupling systems typically include a yoke, a coupler unit, a rotary connector, a pivot pin, and a pin retainer block.
In rotary coupling systems, the coupler has a shank portion with an aperture extending transversely therethrough. The rotary connector is rotatably received in the yoke and has an end opening for receiving the coupler shank. The connector also has a pair of spaced apart coaxial apertures which are alignable with the shank aperture. A pivot pin is insertable into the aligned connector and shank apertures for selectively interconnecting these two components. The yoke has an opening in the bottom wall thereof which is alignable with the connector and coupler shank apertures for permitting selective installation and removal of the pivot pin into and out of association with the connector and coupler shank. A pin retainer block is selectively mountable in a covering relationship with this yoke opening to support the pivot pin and thereby retain the rotary connector and coupler shank in an interconnected relationship.
One problem with prior rotary coupling systems has been in obtaining suitable support for the pivot pin to eliminate uneven or destructive wear on the coupler system components. For example, the pin is not centrally located at both ends thereof in the connector apertures. The pivot pin is received through only a portion of the connector top or upper aperture. When the pivot pin slips downwardly in this upper aperture, rapid wear due to insufficient bearing forms a ledge into the forward wall thereof. This causes premature wear of the connector and necessitates disassembly of the coupler assembly for connector replacement. Also, as the pin tilts forward, it causes eccentric wear to the coupler shank at the rear of its aperture. Still further, difficulty in rotation of the coupler in dump situations has been experienced, particularly under pull conditions, in that the pin is prevented from moving upwardly to free itself due to the presence of the ledge worn into the connector wall by the pivot pin itself.
A partial solution which has been proposed for this problem employs a rubber pad positioned within an opening in a cylindrical pin retainer block. The pin retainer block is held in position by a fastener plate which is secured through aligned openings in the retainer block and in the yoke head. When the fastener is removed, the retainer block can be lowered away from the yoke head. The rubber pad is interposed between the fastener plate and the retainer block. The difficulty with this prior arrangement has been that rubber is not very compressible without undue force, and there is no means provided for initial compression during assembly. Thus a rubber pad does not have the necessary force/travel characteristics even for the intended purpose of taking up slack between the pin retainer block, the fastener plate, and the yoke. Further, the rubber pad does not properly compensate for variations in pivot pin lengths or wear incurred during service.
Accordingly, it has been considered desirable to develop a new and improved pivot pin support structure for a rotary coupler which would overcome the foregoing difficulties and others, and meet the above stated needs while providing better and more advantageous overall results.